The propulsion gas turbine engines installed on many aircraft are housed within a nacelle. Typically, the engine nacelle includes one or more cowl doors. The cowl doors may be moved between stowed (closed) and deployed (open) positions to allow maintenance personnel to access the interior of the nacelle to repair and maintain the engine.
The movement of the cowl doors between the stowed and deployed positions may be accomplished via hydraulic, pneumatic, or electric actuation systems. There may be times, however, that the cowl doors need to be moved when hydraulic, pneumatic, or electric power is unavailable. In such instances, the cowl doors need to be manually moved. To facilitate this, the actuation system may additionally include one or more manual drive units (MDUs). A typical, presently known MDU is configured to receive a specialized tool. An operator, by manually manipulating the tool, may move a cowl door to a desired position. The MDU is preferably provided with a locking mechanism capable of securing the cowl door in the desired position.
Although presently known MDUs are generally safe and reliable, these known MDUs may suffer one or more drawbacks. For example, if an operator applies excessive manual drive force, known MDUs can damage the cowl when impacting stops at the stowed and deployed positions. The locking mechanisms on known MDUs may not automatically engage, and some MDUs allow the specialized tool to remain in place even after it is no longer needed.
Hence, there is a need for a MDU that will not cause damage to the cowl when excessive drive force is applied and/or automatically engages the locking mechanism, and/or does not allow the specialized tool to remain in place after it is no longer needed. The present invention addresses at least these needs.